86Rx7Sil

This car has about 272,000 miles on it. It stopped running. I got it to restart and drove about half way home before it shut off again. It will start but only runs for about two seconds. I thought it was the mass air flow so I replaced it. That didn't help. I tried jumpering the fuel pump circuit and that didn't help. I don't think it is the fuel pump because it always starts so it must be getting fuel. Could it be the relay switch for the fuel pump? I don't know what else it could be.

satch

iTrader: (1)

Sounds like it could be a large vacuum leak. The circuit opening relay (fuel relay) is located underneath the dash and just to the right of the steering wheel column. Relay is Yellow and Black. It has 5 wires, 3 on the top row and 2 on the bottom. Top row far right position is Blue. This wire powers the fuel pump directly on an NA. Turbos are a bit different. If the fuel check connector were jumpered and the key is put to start and it starts up and then dies out you then leave the key just as it is (do not touch the key) and then measure the voltage on the Blue wire in the relay. If there is zero voltage then either the jumper is no good or the relay is problematic. There should be voltage on this wire.

86Rx7Sil

Thanks for your response. I pulled out the manual and checked the circuit opening relay. The ohms check out fine. I pulled it out of the car and looked at the voltage in the connector. The one labeled as "fc" in the manual to the fuel pump switch shows 0 when it should show 12 with the switch on. The one labeled "B" to ignition switch should be 12v and shows 12v. So now I have to figure out where the fc is connected to something and see why its not putting out any voltage.

satch

iTrader: (1)

Instead of using the abbreviations used by the manual just use the wire colors and pin position if the wire colors are the same. Top row far left should have voltage w/key to start. This wire is Black/White. The wire next to it is also B/W but has voltage w/key to on. This wire is powered by the 15 amp engine fuse in the interior fuse box so make sure it is good.

86Rx7Sil

Looks like your car is wired different from mine. None of my wires are black and white. But it does like to me like maybe the Fc wire, the thin black one with a red stripe, should be getting voltage and it is not. Hope this image thing works. I also looked at the connection that I jumpered earlier. I measured the volts across the two and to ground and got nothing. I don't think that is right either.

satch

iTrader: (1)

Fc gets its voltage from the wire which has voltage w/key to on as it is powered by the engine fuse as this voltage bleeds through the relay. If the jumper is in place then Fc will not have voltage w/key to on because the wire being jumperd to it is a ground. So, if you pull the jumper from the ground away from Fc then it should behave as stated in your diagram. To prove this all you would have to do is pull the jumper wire and test Fc w/key to on and it will have voltage, at least it should. Fp is what goes to the fuel pump to power it. If the jumper were in place and key to on it should have voltage. Again, top row far left has voltage w/key to start and the wire to the right of it has voltage w/key to on. And the relay should be plugged in to test it as you measure voltage by back probing the pin location.

And you have yet to state whether your car is a turbo or not as the circuit is different between the two.

86Rx7Sil

The car is a non-turbo. I may have been checking the voltage wrong so I went out to recheck it. When I was rechecking it I noticed the fuel system pressurized when I opened the measuring plate. I blocked the measuring plate open and the car started and ran. It was running very badly which is to be expected I guess. So that narrows the problem down. The mass flow thing is new so that should not be the problem.

86Rx7Sil

I took out the ecu thinking it might be an electrical problem. I wanted to check the voltage and check the harness for ground. When I was doing this my nephew came by with another ecu he got from a friend. I put that one in and the car started up and ran better then it had in years.